Another detail of note is that university students at that time were the country's elite. Which means a large share of them were children of party officials. So

Another detail of note is that university students at that time were the country's elite. Which means a large share of them were children of party officials. So a whole lot of high-ranking members in the CCP had children, or friends who had children, who were injured or killed. And the culture of brainwashing, fear and intimidation was strong enough to keep them in line